Why do some people believe really strange things?

In the U.S. this is mostly from some sort of PTSD in childhood or young adulthood or any time in one's life. It's caused by a fragmentation of a sense of well being usually.

But, it also could be seen as a complete lack of common sense or practicality too. But, often this comes from abuse of one kind or another through wars or medical PTSD or just not feeling safe growing up which can interfere with one's sensibilities moving through life.

I was always lucky to have very good parents even though they both graduated from high School during the 1930s. My father was valedictorian of his High School Class in 1934 and my mother graduated from High school in 1937 I believe.

I found that literally everyone in the 1950s who had survived the Great Depression and World War II had some form of PTSD. This is in some ways what bound them all together in various forms of trauma and woundology. So, the main bonding experience that people had during the 1940s and 1950s was through their traumas and PTSD versions. I knew as. child inherently that some people who were adults you had to just run from so they didn't beat you to death. So, being a child in the 1950s could be very terrifying because in our culture anyone was allowed to discipline a child then sometimes with horrific adults to the point where many children growing up did not survive all this and many were murdered or committed suicide eventually from all these abuses. But, luckily I had good parents and learned to protect myself from crazy adults whose lives were destroyed by the Great Depression and World War II. Mostly I had to know when to run from people like this to survive them. This was what was important to survive people like this in the 1950s. 

Because most people were either too proud or too poor to seek psychological help then during the 1950s. So, all these problems tended to get worse over time because they were not addressed.

You see this sort of problem especially in soldiers, firemen, Police and first responders where people want to advance in their careers so they lie to psychologists and tell them they are okay when they are not.

This is how many families are killed by their soldiers, firemen, police and first responders over time.

I'm not sure how to solve this problem for 1st responders of all kinds but this is an ongoing problem that all societies will have to figure out over time.